1. Field of the Invention
The present invention relates to lead-acid storage batteries, and particularly to small or compact lead-acid storage batteries such as those for motorcycles, which use bolt-insertion-holes as connecting terminals, (i.e., holes through which bolts are inserted for connecting wire harnesses to the terminals).
2. Prior Art Disclosure
Generally, lead-acid storage batteries hereinafter referred to as batteries) for motorcycles include small connecting terminals of bolt-fastening type.
The structures of such connecting terminals however incorporate complex structural components. Various proposals for alternative structures have been made. One of the more useful structures proposed and, which has already been actually manufactured is disclosed in the Japanese first laid-open publication No. 54-48048. In this structure, a connecting terminal which includes bolt-insertion holes and a pole having annular convex rims are integrally formed as a single block or piece out of synthetic resin by injection molding. This type of connecting terminal is called with a terminal. During manufacture, when the cover or lid of a battery and the battery container are heated and welded to each other, the connecting terminal block is also welded to the cover.
Although this structure is superior to all other structures at the present time, it has some practical disadvantages as stated below.
(1) Since the connecting terminal, the pole and the annular convex rims are integrally formed as a block by molding, the block has a complicated shape which may result in defects such as unfilled portions, blowholes, cracks, checks, stress-cracks and deficits in the molding process.
(2) In order to avoid the disadvantages stated in the above item (1), manufacture of the connecting terminal block requires special techniques, such as the formation of vent holes in making the metal molds. Thus, the metal molds can be designed and manufactured only by manufacturers having special expertise.
(3) Further, in order to avoid the disadvantages stated in the above item (1), the manufacture of the block requires severe molding conditions. Thus the blocks can be molded only by foundries having excellent molding techniques.
(4) The block of synthetic resin is formed surrounding a bushing. It is impossible to apply a sufficient molding pressure during the molding of the block, because the pole (provided with the terminal) is thin, especially in the small battery, and thus may be bent by the high pressure.
Therefore, the block and the bushing may loosely fit with each other, thereby allowing leakage of electrolyte.
(5) At the same as the cover and the battery container are heated and welded to each other, the block is welded to the cover. The block has, however, relatively large error in the size (i.e., height), so that the block can not be sufficiently welded to the cover if the height is too small. This may cause leakage of the electrolyte, and further may cause breakage of the welded portion. Breakage of the weld may result in sinking of the connecting terminals when an external force or impact is applied to the terminal from the above.
(6) Generally, the battery for a motorcycle has a relatively large cranking current of about 100 ampere. It is therefore necessary to tightly connect wire harnesses at the vehicle side to the terminals of the battery. For this tight connection, a stress corresponding to a torque of 40 kg-cm or more must be applied from the bolt in the bolt-insertion hole to the connecting terminal. The insufficient welding as stated in the above item (5) would result in immediate breakage of the welded portion.
Accordingly, it is an object of the invention to provide a lead-acid storage battery provided with a terminal assembly which can overcome the above-noted disadvantages such that there is no molding damage in the molded products, metal molds can be easily manufactured, the products can be molded without specialized molding techniques, the leakage of electrolyte through the terminal assembly and the sinking therefrom is prevented, and the terminal assembly will not break even if a stress corresponding to the torque of 40 kg-cm or more is applied from the bolt to the assembly.